Thais cast votes in national elections on Sunday which went smoothly nationwide, although there were 14 pre-election killings across the country.
"There was a shooting in front of the area where authorities were preparing for counting in the town before midnight," police Lieutenant Somsong Raksakaew said on Monday, from Nakhon Sri Thammarat.
"The shooting killed one person and injured three others, including the people who started the shooting. They argued over politics and this escalated into the shooting," he said.
He added that he did not know which party the culprits supported.
Some 210,000 policemen and women were mobilised across the country to ensure a peaceful election in which Prime Minister Thaksin Shinawatra claimed a landslide victory.
Extra forces were dispatched to the kingdom's far south, where a decades-long low-key separatist uprising flared up in January last year, killing more than 580 people since.